The Duchess of Cambridge proves that the trench is the perfect Autumn investment in her old favourite Hobbs coat

Yesterday, the Duchess of Cambridge made the case for deep forest green; after wearing a dark green Dolce & Gabbana dress to watch a volleyball game and tour a food and wine festival in Kelowna, she stepped off the plane in Yukon a few hours later wrapped up against the chill in an emerald trench coat.

Fashion aficionados have long agreed that the trench coat is the most timeless cover-up of them all, but The Duchess of Cambridge's decision to wear one acts as a reminder that it's the ideal transseasonal piece to invest in now- and wear for years.

She first wore the Hobbs 'Persephone' classic belted trench coat, which was previously available for £279, back in 2014 to a St Patrick's Day Parade and two years later it looks as chic as ever. Although this specific style is no longer available, Hobbs' Callaghan military-style trench in a rich burgundy will give a similar look and is currently on sale for £289.

The Duchess of Cambridge wears a forest green Hobbs coatCredit:
Rex

The trench coat is an essential component of what we're calling The 18 hour wardrobe, as it will take you seamlessly from the day to evening, as shown by The Duchess who had a packed schedule, with no slot allocated for a complete outfit change.

When the royal couple arrived in Yukon they spent the evening watching dancers, drummers and musicians perform in 'Land of Gold - A Yukon Cultural Celebration.' The Duchess stayed wrapped up in her trench coat for the duration. This was a smart choice for an on-flight outfit refresh as it co-ordinates with the Dolce & Gabbana midi dress she wore earlier in the day, the frilled hem of which could still be seen peeping out from underneath her trench.

This is the first time that The Duchess of Cambridge, who has worn new pieces by the likes of Jenny Packham and Preen by Thornton Bregazzi this week, has re-worn an item on this royal tour. As well as wardrobe recycling, the Duchess is well-known for flying the flag for the British high street, and so pieces by stalwarts such as L.K. Bennett, Hobbs and Whistles inevitably make it into her royal tour suitcase. This is the second time that the Duchess has worn the high street while in Canada, as earlier this week she wore a pair of Zara skinny jeans with a shooting jacket.

The Duchess of Cambridge wears Dolce & Gabbana earlier in the dayCredit:
Rex

The Duchess's Tuesday evening outfits came with the requisite respectful nod to Canada. As she stepped off the plane in Yukon she made sure her outfit paid tribute to her host country by carrying a classic maple leaf tartan scarf over her arm. The maple leaf tartan was designed to use all of the colours of the maple leaf changing through the seasons and it became an official national symbol in 2011. The fact that the Duchess carefully displayed the scarf over her arms rather than wearing it around her neck signifies that this is an accessory with a distinct diplomatic purpose.

Each outfit the Duchess has worn so far has featured an element of host nation flattery; Kate's red Preen dress was a nod to Canada's national colours, which was completed with The Queen's maple-leaf brooch. On Day 2 of the tour, she wore a red and white printed custom Alexander McQueen dress which once again was a clever use of Canada's national colours.

If you're sold on a new-season trench, see below for our guide for the ways to style yours this Autumn...